In the framework of the relativistic mean field theory, the isovector scalar interaction is considered by exchanging delta meson to study the influence of delta meson on the cooling properties of neutron star matter. The calculation results show that with the inclusion of delta meson, the neutrino emissivity of the direct Urca processes increases, and thus enhances the cooling of neutron star matter. When strong proton superfluidity is considered, the theoretical cooling curves agree with the observed thermal radiation for isolated neutron stars.